The field of the invention is pharmaceutical chemistry.
K-252a is an indolocarbazole whose stereochemistry is shown below (Formula I): 
K-252a inhibits protein kinase C (PKC), which plays a role in regulating cell functions. K-252a has various activities, e.g., inhibiting smooth muscle contraction (Jap. J. Pharmacol. 43 (suppl.): 284, 1987), inhibiting serotonin secretion (Biochem. Biophys. Res. Commun. 144: 35, 1987), inhibiting elongation of neuraxone (J. Neurosci. 8:715, 1988) inhibiting histamine release (Allergy 43:100, 1988), inhibiting smooth muscle MLCK (J. Biol. Chem. 263:6215, 1988), anti-inflammatory action (Acta Physiol. Hung. 80:423, 1992), and promotion of cell survival (J. Neurochem. 64:1502, 1995). K-252a also inhibits IL-2 production (Exper. Cell Res. 193:175-182, 1991). The total synthesis of the natural (+) isomer of K252a and its enantiomeric (xe2x88x92) isomer (all three chiral carbons of the sugar moiety inverted), has been achieved (Wood et al., J. Am. Chem. Soc. 117:10413, 1995; and WO 97/07081).
We have discovered that certain 3xe2x80x2-epimeric derivatives of K-252a are biologically active. These compounds have the following general formula (Formula II): 
wherein:
R1 and R2 independently are:
hydrogen; lower alkyl; halogen; acyl; nitro;
sulfonic acid;
xe2x80x94CHxe2x95x90NR4, wherein R4 is guanidino, heterocyclic, or xe2x80x94NR5R6, wherein R5 or R6 is hydrogen or lower alkyl, and the other is hydrogen, lower alkyl, acyl, aryl, heterocyclic, carbamoyl or lower alkylaminocarbonyl;
xe2x80x94NR5R6;
xe2x80x94CH(SR7)2 wherein R7 is lower alkyl or alkylene;
xe2x80x94(CH2)jR8, wherein j is 1-6, and R8 is halogen; substituted aryl; unsubstituted aryl; substituted heteroaryl; unsubstituted heteroaryl; N3;
xe2x80x94CO2R9, wherein R9 is hydrogen, substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, unsubstituted aryl, substituted heteroaryl, or unsubstituted heteroaryl;
xe2x80x94C(xe2x95x90O)NR10R11, wherein R10 and R11 independently are hydrogen, substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, unsubstituted aryl, substituted heteroaryl, unsubstituted heteroaryl, substituted aralkyl, unsubstituted aralkyl, lower alkylaminocarbonyl, or lower alkoxycarbonyl, or R10 and R11 are combined with a nitrogen atom to form a heterocyclic group;
xe2x80x94OR12, wherein R12 is hydrogen, substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, unsubstituted aryl; or xe2x80x94C(xe2x95x90O) R13, wherein R13 is hydrogen, NR10R11, substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, unsubstituted aryl, substituted heteroaryl, unsubstituted heteroaryl, substituted aralkyl, or unsubstituted aralkyl;
xe2x80x94NR10R11;
xe2x80x94C(xe2x95x90O)R14, wherein R14 is hydrogen, lower alkyl, substituted aryl, unsubstituted aryl, substituted heteroaryl, or unsubstituted heteroaryl;
xe2x80x94S(xe2x95x90O)rR15, wherein r is 0 to 2, and R15 is hydrogen, substituted lower alkyl, unsubstituted lower alkyl, substituted aryl, unsubstituted aryl, substituted heteroaryl, unsubstituted heteroaryl, substituted aralkyl, unsubstituted aralkyl, thiazolinyl, (CH2)aCO2R16, wherein a is 1 or 2, and R16 is hydrogen or lower alkyl, or xe2x80x94(CH2)aC(xe2x95x90O) NR10R11;
xe2x80x94OR17, wherein R17 is hydrogen, lower alkyl, or xe2x80x94C(xe2x95x90O)R18, wherein R18 is substituted lower aIkyl, unsubstituted lower alkyl, substituted aryl, or unsubstituted aryl;
xe2x80x94C(xe2x95x90O)(CH2)jR19, wherein R19 is hydrogen, halogen, NR10R11, N3, SR15, or OR20, wherein R20 is hydrogen, substituted lower alkyl, unsubstituted lower alkyl, or C(xe2x95x90O)R14;
xe2x80x94CH(OH)(CH2)jR19;
xe2x80x94(CH2)dCHR21CO2R16A, wherein d is 0-5, and R21 is hydrogen, CONR10R11, or CO2R16A, wherein R16A is the same as R16;
xe2x80x94(CH2)dCHR21CONR10R11;
xe2x80x94CHxe2x95x90CH(CH2)mR22, wherein m is 0-4, and R22 is hydrogen, lower alkyl, CO2R9, substituted aryl, unsubstituted aryl, substituted heteroaryl, unsubstituted heteroaryl, OR12, or NR10R11;
xe2x80x94CHxe2x95x90C(CO2R16A)2;
xe2x80x94Cxe2x95x90xe2x80x94C(CH2)mR22;
xe2x80x94SO2NR23R24, wherein R23 and R24 independently are hydrogen, lower alkyl, or groups that form a heterocycle with the adjacent nitrogen atoms;
xe2x80x94OCO2R13A, wherein R13A is the same as R13; or
xe2x80x94OC(xe2x95x90O)NR10R11;
R3 is hydrogen; lower alkyl; carbamoyl; amino; tetrahydropyranyl; hydroxyl; C(xe2x95x90O)H; aralkyl; lower alkanoyl; or CH2CH2R25, wherein R25 is halogen, amino, di-lower alkylamino, hydroxyl, or hydroxysubstituted lower alkylamino;
X is hydrogen; formyl; carboxyl; lower alkoxycarbonyl; lower alkylhydrazinocarbonyl; xe2x80x94CN; lower alkyl;
xe2x80x94C(xe2x95x90O)NR26R27, wherein R26 and R27 independently are hydrogen, unsubstituted lower alkyl, or unsubstituted aryl; or R26 and R27 are combined with a nitrogen atom to form a heterocyclic group;
xe2x80x94CH(R34)W, wherein R34 is hydrogen or lower alkyl, and W is xe2x80x94Nxe2x95x90CHN(alkyl)2; guanidino; N3; NR28R29, wherein R28 or R29 is hydrogen or lower alkyl, and the other is hydrogen, allyl, alkanoyl, aryloxycarbonyl, unsubstituted alkyl, or the residue of an xcex1-amino acid in which the hydroxy group of the carboxyl group is excluded; xe2x80x94CO2R9; xe2x80x94C(xe2x95x90O)NR10R11; xe2x80x94S(xe2x95x90O)rR30, wherein R30 is substituted or unsubstituted lower alkyl, aryl, or heteroaryl; or xe2x80x94OR31, wherein R31 is hydrogen, substituted or unsubstituted alkyl, or substituted or unsubstituted alkanoyl;
xe2x80x94CHxe2x95x90Nxe2x80x94R32, wherein R32 is hydroxyl, lower alkoxy, amino, guanidino, ureido, imidazolylamino, carbamoylamino, or NR26R27A (wherein R26A is the same as R26 and R27A is the same as R27); or
xe2x80x94CH2Q wherein Q is a sugar residue represented by 
xe2x80x83wherein V represents hydrogen, methyl, ethyl, benzyl, acetyl, or trifluoroacetyl;
Y is hydrogen; xe2x80x94OH; xe2x80x94OC(xe2x95x90O)R33, wherein R33 is alkyl, aryl, or amino; xe2x80x94OCH2O-alkyl; xe2x80x94O-alkyl; aralkyloxy; or X and Y are combined as xe2x80x94Xxe2x80x94Yxe2x80x94to form, xe2x80x94CH2OCO2xe2x80x94 or xe2x80x94CH2N(R16B)CO2xe2x80x94 (wherein R16B is the same as R16);
A1 and A2 are hydrogen, or both are combined to represent O; or B1 and B2 are hydrogen, or both are combined to represent O; or a pharmaceutically acceptable salt thereof; with the proviso that at least one of A1,A2 or B1,B2 represents O; and with the further proviso that both X and Y are not simultaneously hydrogen.
Preferably, X is xe2x80x94C(xe2x95x90O)NR26R27, carboxyl, lower alkoxycarbonyl, formyl, lower alkyl, xe2x80x94CH2OR31, xe2x80x94CH2NR28R29, or xe2x80x94CH2S(O)rR30. Preferably, R1 and R2 are H. Preferably, R3 is hydrogen or a protecting group. Particularly preferred are Compounds VI, VII, VIII, X, XII, XIV, XV, XVI, XVII, XVIII, XIX, XXV, and XXVII, shown below: 
In some embodiments of the invention, 3xe2x80x2-epimeric K252a derivatives are formulated into pharmaceutical compositions.
The invention also provides a method for inhibiting the activity of a tyrosine kinase, for example, protein kinase C (PKC). The method includes contacting the tyrosine kinase with a compound of claim 1. The tyrosine kinase can be in vivo or in vitro.
The invention also provides a method for inhibiting the phosphorylation of a tyrosine kinase by a second kinase. The method includes contacting the second kinase with a compound of claim 1. The tyrosine kinase can be in vivo or in vitro.
The invention also provides a method for enhancing the function of a cholinergic neuron. The method includes contacting the cholinergic neuron with a compound of claim 1. The cholinergic neuron can be in vivo or in vitro.
The invention also provides a method for enhancing the survival of a cholinergic neuron. The method includes contacting the cholinergic neuron with a compound of claim 1. The cholinergic neuron can be in vivo or in vitro.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present application, including definitions will control. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference.
Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described below. The materials, methods, and examples are illustrative only and not intended to be limiting. Other features and advantages of the invention will be apparent from the detailed description, and from the claims.